The invention relates to an apparatus for applying a fluid coating substance such as an adhesive, sealing material, coating material etc. and more particularly, to an apparatus for intermittently applying those coating substances to an object such as a workpiece or substrate at a high speed.
High speed intermittent application of adhesives is effective in the use of heat fused adhesives so that setting and adhesion completion time are short, based on the characteristics of the adhesive. Heat fused adhesives are used and have wide applications since there is a great need for this use. Known apparatus for intermittent application of heat fused adhesives are of many types utilizing a valve system with either needle or ball valves. In such known apparatus the valve stem, utilizing either a needle or ball, is connected to a pneumatic piston. The movement of the piston is effected by compressed air controlled by a flow control valve, and a needle or ball valve either opens or closes an orifice and the apparatus intermittently discharges heated adhesive from the orifice. Also an apparatus in which a valve stem moves up and down by electromagnetic force of solenoids instead of compressed air is known, and it controls the opening and closing of the orifice.
However, it is known these apparatus are inadequate for high speed operational requirements which are now needed and there are also the same type problems on the maintenance thereof. By using the above known valve system, discharge and stopping are repeated at high speed. The result is an intermittent discharging time which is controllable within 15/1000 second minimum and the maximum repetitive limit per minute is about 300 times. Moreover, the use of compressed air becomes a source of noise due to repeated sound resulting from the flow control valve. Furthermore since a supply source for compressed air is necessary, the apparatus is complicated. In controlling the known apparatus by using electromagnetic force, it is difficult to obtain satisfactory operation at high speeds. Especially, heat fused adhesives must be heated, so this heating has a negative influence on the operation of solenoids. Thus there are constructional defects in such apparatus. There are other known apparatus for intermittent application such as a gravure roll coater, stack coater, stamp coater etc., but these also have many problems when in use in comparison to the above mentioned valve system in relation to high speed intermittent application of an adhesive, the practical application of applying a pattern, the precision of amount applied and the like.